The present invention relates generally to a damper assembly used to control movement/vibration in a mechanical system or the like. More specifically, the present invention relates to a fluid-elastomeric damper assembly including an internal pumping mechanism. The fluid-elastomeric damper assembly may be used, for example, to control movement/vibration in the lead-lag direction of the rotor of a rotary-wing aircraft or the like.
Conventional fluid-elastomeric damper assemblies (also referred to as xe2x80x9cfluidlastic(copyright)xe2x80x9d damper assemblies) typically incorporate an elastomer seal, such as a rubber seal or the like, containing a fluid, such as hydraulic fluid or the like. This elastomer seal is bonded, fixedly attached, or otherwise coupled to the major metal components of the fluid-elastomeric damper assembly which are, in turn, fixedly attached or otherwise coupled to one or more moving/vibrating structures. These moving/vibrating structures may include, for example, the flex-beam and the pitch case of the rotor of a rotary-wing aircraft or the like. The elastomer seal is used to pump the fluid through a restriction, such as one or more orifices or the like, creating an increase in the fluid pressure which reacts against the elastomer seal surface, resulting in a damping force resisting the movement/vibration of the one or more moving/vibrating structures. The fluid may be pumped, for example, from one chamber disposed within the elastomer seal or an associated structure to another chamber disposed within the elastomer seal or an associated structure, or from one chamber formed by the major metal components of the fluid-elastomeric damper assembly to another chamber formed by the major metal components of the fluid-elastomeric damper assembly.
Advantageously, the elastomer seal is substantially leak-resistant and is capable of accommodating movement/vibration in a plurality of directions. However, in order to create a desired damping force, the volume stiffness, i.e., the elastomer stiffness reacting the fluid pressure, of the fluid-elastomeric damper assembly must be sufficiently high and the observed increase in the stiffness of the elastomer seal which results from the increased fluid pressure must be limited to within a predetermined range. This is not always possible, for example, in the control of movement/vibration in the lead-lag direction of the rotor of a rotary-wing aircraft or the like.
Thus, what is needed is a fluid-elastomeric damper assembly including one or more elastomer seals, but also including an internal pumping mechanism that does not rely on the one or more elastomer seals to pump the fluid through the restriction, i.e., through the one or more orifices. This would allow for the creation of relatively higher damping forces in relation to the elastomer stiffness for resisting relatively greater movement/vibration of the one or more moving/vibrating structures than is possible with conventional fluid-elastomeric damper assemblies. Although the assemblies, mechanisms, and methods of the present invention are described herein below in conjunction with the flex-beam and the pitch case of the rotor of a rotary-wing aircraft or the like, the assemblies, mechanisms, and methods of the present invention may be used in conjunction with any mechanical system or the like including one or more moving/vibrating structures that it is desirable to damp.
In various embodiments of the present invention, a fluid-elastomeric damper assembly includes at least a first elastomer seal, such as a rubber seal or the like, disposed at a first end of the fluid-elastomeric damper assembly and a second elastomer seal, such as a rubber seal or the like, disposed at a second end of the fluid-elastomeric damper assembly. The first elastomer seal is fixedly attached or otherwise coupled to a first moving/vibrating structure, such as a flex-beam of the rotor of a rotary-wing aircraft or the like, and the second elastomer seat is fixedly attached or otherwise coupled to a second moving/vibrating structure, such as a pitch case of the rotor of a rotary-wing aircraft or the like. The first elastomer seal and the second elastomer seal are both bonded, fixedly attached, or otherwise coupled to a housing structure including, for example, a first housing member and a second housing member. Together, the first elastomer seal, the second elastomer seal, and the housing structure are operable for containing a fluid, such as hydraulic fluid or the like. An internal pumping mechanism including one or more piston structures and a piston structure housing is also disposed within the housing structure. The internal pumping mechanism is grounded to or integrally formed with the first moving/vibrating structure and moves in relation to the housing structure and the second moving/vibrating structure to which the housing structure is grounded. The internal pumping mechanism is configured such that, when the internal pumping mechanism moves with respect to the housing structure and the second moving/vibrating structure, the fluid surrounding and disposed within the internal pumping mechanism is pumped from a first chamber disposed within each of the one or more piston structures to a second chamber disposed within each of the one or more piston structures through a restriction, i.e., an orifice. Optionally, the relative size of the restriction is controlled by an adjustable pressure relief device and/or a temperature-compensating device. Advantageously, the first elastomer seal, the second elastomer seal, and the housing structure provide a fluid-elastomeric chamber operable for containing the fluid and in which the internal pumping mechanism may be submerged. This fluid-elastomeric chamber is flexible and allows the internal pumping mechanism to damp movement/vibration in a primary direction with a relatively high damping force. Additionally, movement/vibration in a plurality of other directions are accommodated by the internal pumping mechanism by design, without damping force.
In one embodiment of the present invention, a fluid-elastomeric damper assembly includes a housing structure, a first elastomer seal coupled to the housing structure, and a second elastomer seal coupled to the housing structure. The housing structure, the first elastomer seal, and the second elastomer seal define a fluid-elastomeric chamber operable for containing a fluid. The fluid-elastomeric damper assembly also includes an internal pumping mechanism disposed within the fluid-elastomeric chamber.
In another embodiment of the present invention, a fluid-elastomeric damper assembly operable for damping relative motion between a first structure and a second structure includes a housing structure coupled the first structure, a first elastomer seal coupled to the housing structure, wherein the first elastomer seal is also coupled to the second structure, and a second elastomer seal coupled to the housing structure. Again, the housing structure, the first elastomer seal, and the second elastomer seal define a fluid-elastomeric chamber operable for containing a fluid. The fluid-elastomeric damper assembly also includes an internal pumping mechanism disposed within the fluid-elastomeric chamber, wherein the internal pumping mechanism is coupled to the second elastomer seal.
In a further embodiment of the present invention, a fluid-elastomeric damper assembly operable for damping relative motion between a first structure and a second structure includes a housing structure grounded to the first structure and a plurality of elastomer seals coupled to the housing structure, wherein the housing structure and the plurality of elastomer seals define a fluid-elastomeric chamber operable for containing a fluid. The fluid-elastomeric damper assembly also includes one or more piston structures disposed within the housing structure and the fluid-elastomeric chamber, wherein the one or more piston structures are grounded to the first structure and driven by the second structure, and wherein the one or more piston structures each include a first substantially fluid-filled chamber and a second substantially-fluid-filled chamber in communication via an orifice, the first substantially fluid-filled chamber and the second substantially fluid-filled chamber also in communication with the fluid-elastomeric chamber. The housing structure is operable for pumping the fluid through the orifice.
In a still further embodiment of the present invention, a method for damping relative motion between a first structure and a second structure includes grounding a housing structure to the first structure, coupling a plurality of elastomer seals to the housing structure, wherein the housing structure and the plurality of elastomer seals define a fluid-elastomeric chamber, and disposing a fluid within the fluid-elastomeric chamber. The method also includes disposing one or more piston structures within the housing structure and the fluid-elastomeric chamber and grounding the one or more piston structures to the first structure, wherein the one or more piston structures each include a first substantially fluid-filled chamber and a second substantially-fluid-filled chamber in communication via an orifice, the first substantially fluid-filled chamber and the second substantially fluid-filled chamber also in communication with the fluid-elastomeric chamber. Again, the housing structure is operable for pushing the fluid through the orifice. The method further comprising driving the one or more piston structures with the second structure.